It is well known that some materials take up water from moist air. Cellulose and diatomaceous earth are the examples of such materials. The skilled man knows several others. When the material becomes saturated with moisture, no further moisture can be taken up. But the materials can be regenerated (i.e. remove the moisture) with heat. Hot air can be used for regeneration or the materials can simply be put into a container which is then heated.
The absorbing or adsorbing technique and further regeneration is well known. But the regeneration of drying material is to some extent new. In the present inventor's Swedish patent SE 454 849, microwaves are used to regenerate drying materials. The distribution of these waves at a normal atmospheric pressure level is the problem that the present invention deals with.
Drying of compressed air is important for the vessels that contain that air. Here, NO 154 419 and EP 016 385 of a U.S. inventor teach the same heating technique but without the problem of spreading the microwaves over as large a surface as is necessary in ordinary air drying at an atmospheric pressure level. PCT/US78/00128 treats other materials saturated with other gases than the present invention.